Door mounted down draft flue for wood burning stoves



Dec. 16, 1958 G. w. HARDING 2,864,358

DOOR MOUNTED DOWN DRAFT FLUE FOR woon BURNING STOVES Filed June 30, 19541N VENTOR fi. )Y/Ymd BY WM ATTORNEYE United States Patent DOOR MOUNTEDDOWN DRAFT FLUE FOR WOOD BURNING STOVES George W. Harding, Lynchburg,Va., assignor to Automatic Draft and Stove Co., Inc., Lynchburg, Va.

Application June 30, 1954, Serial No. 440,428

4 Claims. (Cl. 126--77) This invention relates to down draft woodburning heating stoves. In such stoves, as in all other stoves for thatmatter, it is logical and conventional to have the smoke pipe connectionat the rear, since the back of the stove is adjacent the chimney. Thisnecessitates that the down draft pipe be at the front, which is alsoconventional, since for efliciency the air intake should be as remote aspossible from the smoke pipe.

Obviously, since the front of the stove is occupied by the down draftpipe, the only place for the fuel door is at the top of the stove, andinsofar as is known to applicant, all down draft wood burning stovesheretofore have had the fuel door on top. This high location of the fueldoor requires that the chunks of wood which are generally heavy, belifted the full height of the stove, and users have often wished that itwere practicable to put in the fuel at a lower level.

The present invention has for its object to provide a down draft woodburning stove having a door at the front, closing an opening in thebodywall of the stove, the down draft flue being on the inside of the stoveat the front, and having at least that portion which would normallyobstruct the door opening, incorporated in the door so as to move withthe door out of obstructive relation to the door opening when the dooris opened.

- Other objects of the invention will appear as the followingdescriptionof a practical embodiment thereof proceeds. I 1

In-the drawing which accompanies. and forms a part of the followingspecification, and throughout the figures of which the same referencecharacters have been used to denote identical partsr Y I Figure 1 is aperspective view of a stove of the type described, embodying theprinciples of the invention;

Figure 2 is a section taken along the line 2-2 of Figure 1;

Figure 3 is a view similar to Figure 1, showing a modified embodiment ofthe invention;

Figure 4 is a section taken along the line 4-4 of Figure 3;

Figure 5 is a section taken along the line s-5 of Figures 2 and 3.

Referring now in general to the drawing, it may be stated that while theinvention comprehends broadly any down draft stove that has both thefuel door and the down draft flue at the front, the specific stoveselected by Way of illustration is one in which the down draft isregulated by a damper controlled by a thermostat mounted in heatexchanging relation to the stove structure at the upper end of the downdraft flue, responsive predominantly to stove temperature, but having amodicum of control derived from room temperature effective when the firebecomes low to keep the damper open to a greater extent than it would bein response to stove temperature, to prevent the combustion fromdiminishing to the point at which the fire dies out. The specificthermostatic damper used as shown is fully described and covered in myco-pending application. Serial No. 403,497, filed January 12, 1954, nowPatent No. 2,797,874, and is not per se herein claimed.

Adverting now in detail to Figures 1, 2 and 5, the stove as showncomprises a curved body 1 with top 2,

and bottom. 3. The lower part of the space within the stove may beconsidered the combustion chamber to which chunks of wood are suppliedthrough an opening 4 in the front of the body, located at anintermediate point in the height thereof, having its lower edge abovethe bottom of the combustion chamber and being closed by a curved door 5conforming to the curvature of the body and hinged at one side so as toopen outwardly.

Within the body at the front is a flat plate 6 extending downward from apoint above the door substantially to the level of the bottom of thedoor opening, said plate being flanged at the sides and being of suchwidth as to assume chordal relationship to the curvature of the doorwhen applied to the door. This plate is transversely divided at thelevel of the upper edge of the door opening into two sections, the uppersection 7 being secured to the body of the stove and the lower section8, to the door, by fastening means such as stove bolts engaging the sideflanges. The two sections of the plate 6 are in registry when the dooris closed, constituting with the door and with the part of the body thatthey subtend, a down draft flue 9. The lower part of the down draft flueswings outward with the door, leaving unobstructed space back of thedoor for the insertion of the chunks of wood into the combustionchamber.

The upper part of the down draft flue 9 communicates with an opening 10in the body of the stove located above the door opening. The uppersection 7 of the plate 6 has a forwardly extending upper end forming atop closure within the stove and the down draft flue, its forward edgefitting closely the curvature of the stove body abovesthe-upper edge ofthe opening 10.

Said opening forms a passage from the down draft controls the intake ofair to the combustion chamber by" way of the down draft flue. The damperis controlled by a thermostat 15 within the casing 12, which is inthermal contact with the damper shaft and in heat exchanging proximityto the stove structure so that it responds predominantly to stove andnot room temperature. However, in order to subject the damper operationto a minor factor of control responsive to room temperature, thethermostat is located in a vertical duct 16 open to atmosphere at bothends, through which a convection current of relatively cool room aircontacts the thermostat during operation of the stove. While combustionis active, the heat from the stove to which the thermostat responds faroutweighs the room temperature control factor, but when combustiondiminishes, relatively cool room air accelerates the opening of thedamper so that combustion is stimulated before the fire gets too low tobe revived,

Figures 3 and 4 disclose a modification of the invention in which theentire down draft flue and including the there mostatic damper controlunit are carried by the door, In this form of the invention the door isprovided with an opening 18 therethrough in its upper part and carrieson its inner side the flat laterally flanged plate 19 in chordalrelation to the curvature of the door, and which is similar to thesection f the plate 6 present in the Patented Dec. 16, 1958" firstdescribed modification of the invention. On the outside, ofthe. door isthe casing12 defining the duct 13, which communicates through theopening 18 with the down draft fiue defined between the plate 19 and theportion ofl'the: door which it subtends; 12 isrsimila-r or identicalwith the-one illustrated in Figure 2, it is constructed to provide theduct lm in which the; thermostat l5 isr located, being fixedat one-endto the shaft 16: of the damper 14 The plate 19- is-angularly deflectedtoward the: door at the top -simila-rito theplate sectionlin Figure 2,with itswedget conforming to the curvature of the doorandgfittingclosely thereagainst in a substantially: airtight manner.formsrohthe invention, is. thatathesentire thermostatic dampercontrolleddown draft feature iswholly. carried by the. door;,-forrns part of thedoor structure, and can be manufactured and; sold with the door asa partthereof, and, installed; on wood stove bodies. having a suitableopening: at, the. front.

While I have in the above description disclosed practical embodiments ofthe broad inventive principle, it will be, understood by those, skilledin. the art that the main coneeptof, the invention is a wood burningstove having a down draftat the front with at least a part of the downdraft, fiuecarried by the door and movable, therewith so that it is outof obstructive position, when the door is opened, with. respect to theintroduction of fuel into the stove. It will also be understood that thebroad concept of, the, invention includes anystructural means of formingthe down draft flue, which is whollyor partially carried by the door atthe front of the stove,

1. Wood burning stove'comprising a hollow body having its front wall ofcylindrical curvature about an upright axis,, and havingafuel accessopening in the front wall at an intermediate point between, the top andbottom of, said body, a laterally hinged door for closing said opening,forming part of the front wall of said body, a planiform partition platewithin said body extending vertieally upward, from a level adjacent thebottom thereof, intersecting the inward geometrical projection of saidfuelaccess opening, said plate being in chordal relation to thefrontwallof said body defining with said front wall the inner limb of adown draft flue, said inner limb being ofsubstantiallyuniformcross-sectional shape and area throughout the .lengthof saidplate, a fitting on the outer side of said cylindical front wallpartitioned to form a conduit adjacent said front wall constituting theouter limb, of said down draft flue, open to atmosphere at the top andcommunicating with said inner limb through an Since the-lcasing Theadvantage of this i opened;

2. Wood burning stove as claimed in claim 1, said fitting being mountedon said front wall above said fuel access opening.

3. Wood burning stove comprising a hollow cylindrical body forming anenclosure defining a grateless combustion chamber having an unobstructedfuel access opening at the front at an intermediate position in theheight of said enclosure, the latter including a laterally hinged doorfor closing said opening, a partition within said enclosure at thefront, forminga down draft flue in conjunction with said enclosure, somuch of said partition as is in conjunction with said door beingswingable unitarily therewith,

said down draft fiuehaving its lower end terminating at a level adjacentthe bottom ofsaid door opening andextending upward therefrom, and havinganair inlet opening through said enclosure at its upper end, a casing onthe outer side of said enclosure overlying said inlet open ingconstituting the outer limb-of said down draft flue, a damper withinsaidcasing controlling the inlet of air to said down draft flue, athermostat within said casing having itsthermal element connectedmetallically tosaid enclosure to respond predominantly to stovetemperature, said casing being open at top and bottom respectively overand under said thermostat, providing for an upward con vection flow ofair at room temperature about said-thermostat.

4'. Wood burning stove as claimed in claim 3, said air inlet openingbeingrin said door, and said casing damper and thermostatbeing carriedby said door.

References Cited in the file of thispatent UNITED. STATES PATENTS610,260 Culter Sept. 6, 1898' 666,460 Blanchard Jan. 22, 1901 938,543Anthony Nov. 2, 1909 2,170,728 Montague Aug. 22, 1939 2,199,875 BrogdenMay 7, 1940 FOREIGN PATENTS 2,733 Great Britain Sept. 13, 1872

